Dynamically variable machine readable binary code and method for reading and producing thereof

ABSTRACT

A machine readable binary code which is dynamically variable in size, format and density of information is provided. The binary code is formed as a matrix having a perimeter and data contained therein. The perimeter is provided with density indicia for indicating the density of data contained within the matrix. The perimeter is also provided with size indicia for indicating the size of the matrix. By utilizing the density indicia and size indicia, a scanning device is able to calculate the size and information density of the binary code.

This is a continuation of U.S. patent application Ser. No. 07/907,769,filed Jun. 30, 1992 now U.S. Pat. No. 5,329,107; which is a continuationof U.S. patent application Ser. No. 07/627,080, filed on Dec. 13, 1990,which is now U.S. Pat. No. 5,126,542; which is a continuation of U.S.patent application Ser. No. 07/513,362, filed Apr. 24, 1990 and is nowU.S. Pat. No. 5,033,609; which is a continuation of U.S. patentapplication Ser. No. 07/190,205, filed May 5, 1988, which is now U.S.Pat. No. 4,939,354.

BACKGROUND OF THE INVENTION

This invention relates to a binary code which is optically readable by amachine, and in particular, to a binary code which allows for dynamicvariability.

Optically readable codes are known in the art. One such code is formedas a "checker board" symbol that represents information in the form ofblack and white squares. Each square contained within the checker boardmatrix is of equal size to every other square. Furthermore, the numberand size of the squares contained within the matrix is predetermined,accordingly the computer receiving or producing the data expects aspecific number of squares contained within the matrix each being of apreset size. This code has not been satisfactory. The code is unable todynamically expand or contract data capacity to meet changing userrequirements without the intervention of re-programming the software ofthe scanning computer. Accordingly, the user of the code must identifythe data requirement prior to implantation of the software system.Additionally, since each square must be of the exact same size and thenumber of squares is predetermined, the scanning computer must be presetfor the expected matrix size thereby limiting the user to a single sizedchecker board code for each scanner. This necessitates a plurality ofcode scanners and a system for separating each different sized,different density code and forwarding it to the appropriate scanner.

Codes which overcome these shortcomings by providing indicia associatedwith the code for informing the computer as to the size of the code areknown in the art. One example of such a code is U.S. Pat. No. 3,763,467which discloses the optical reading of data set up in box fashion upon acard. The card is marked at its periphery with two field defining markslocated at the front and trailing edges of the box indicating the sizeof the field containing binary code decimal data stored within the box.The first row of data within the box, forming the perimeter edge,contains format information identifying which of the columns within thebox is to be read. This code has also been less than satisfactory inthat it suffers from density and size problems. Even though the size ofthe field is variable the actual size of the characters within the fieldis not, accordingly a smaller field size results in smaller amounts ofstored information. Furthermore, the size indicia being read must be ina particular location in order to be received and understood by thescanning equipment.

Accordingly, it is desirable to provide a dynamically variable machineoptically readable binary code and method for reading and producingthereof which overcomes the shortcomings of the prior art devicesdescribed above.

SUMMARY OF THE INVENTION

Generally speaking, in accordance with the invention, an opticallyreadable binary code which is dynamically variable in size, format anddensity of information is provided. The code is formed of a matrixcontaining data having a first side and a second side each being formedof identical broken line patterns of alternating darkened and lightenedareas. The first side and second side intersect at a first corner. Theproduct of the number of lightened areas and darkened areas of the firstside and the number of lightened areas and darkened areas of the secondside corresponds to the amount of information contained within the code.A third side and a fourth side are each formed as a solid line of equaldarkness intersecting at a second corner. The solid lines correspond tothe length, height and area of the code.

The information contained within the code perimeter may appear once or anumber of times providing redundancy in the recorded information. Theinformation may also be stored in a plurality of patterns within thematrix.

The code is read by an optical scanner and by measuring the solid blacklines the physical size of the matrix is determined. By scanning thebroken line pattern of the other perimeter sides, the amount ofinformation contained within the matrix may be determined. The computermay then independently determine both size and density of the matrixbeing scanned.

Accordingly, it is an object of this invention to provide an improvedoptically readable binary code.

Another object of this invention is to provide an optically readablebinary code which allows a scanning computer to independently recognize,understand and act upon the encoded information regardless of the actualphysical size or volume of data contained within the symbol.

A further object of this invention is to provide an optically readablebinary code which may be read and processed regardless of the angleorientation of the symbol to the scanner.

Yet another object of this invention is to provide an optically readablebinary code which may dynamically encode large quantities of informationin any physical size.

Still another object of this invention is to provide an opticallyreadable binary code which enables the computer to independentlyrecognize and decode the information contained within the coderegardless of the physical size, data density, or angle of rotation ofthe code relative to the reader.

Yet another object of this invention is to provide an optically readablebinary code which allows the density of the code matrix to bedynamically determined and computer generated without requiring userinvolvement.

Yet another object of the present invention is to provide an opticallyreadable binary code and method for processing thereof which gives theuser absolute control over a selection of a physical size of the code aswell as the volume of the data which is encoded therein.

Still other objects and advantages of the invention will in part beobvious and will in part be apparent from the specification anddrawings.

The invention accordingly comprises the several steps in their relationof one or more such steps with respect to each of the others and thearticle possessing features, properties and relation of elements, whichare exemplified in the following detailed disclosure, and the scope ofthe invention will be indicated in the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

For a fuller understanding of the invention, reference is had to thefollowing description, taken in connection with the accompanyingdrawings, in which:

FIGS. 1a and 1b depict two binary codes in accordance with theinvention; of different sizes, but containing the same information;

FIGS. 2a-2d illustrate the arrangement of data within the perimeter ofthe binary code in accordance with the invention;

FIGS. 3a-3d illustrate the redundant rotation of visual cells within thematrix in accordance with the invention;

FIG. 4 is a block diagram of an apparatus for processing and scanningthe code in accordance with the invention; and

FIG. 5 is a flowchart depicting the process for reading the binary code.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Reference is made to FIG. 1a, wherein a binary code, generally indicatedas a matrix 10, constructed in accordance with the invention ispresented. Binary code matrix 10 has a perimeter 11 formed byintersecting sides 12 formed of solid lines and intersecting perimetersides 14 formed of dark perimeter squares 16 and light perimeter squares18 in an alternating pattern. Data, generally indicated as 19, is storedwithin perimeter 11 of matrix 10.

Data 19 is stored within the perimeter of matrix 10 by converting eachcharacter to be stored into a visual binary code represented by dark andlight squares corresponding to ones and zeros of binary information.Accordingly, a letter or number represented by the binary code 0001 maybe represented by a string of data cells, each cell containing either adark square or light square. Accordingly, the data representing 0001would appear as a series of three light data cells and one dark datacell. For example, the numbers 0 through 9 are stored within matrix 10as a pattern of light cells 20 and dark cells 22.

Binary representation of the one hundred twenty-eight (128) US-ASCIIletters, numbers and symbols requires eight binary bits, or in the caseof matrix 10, eight visual squares or cells to represent a character.However, by defining the maximum range of characters that may appear ateach position of the input string, it is possible to suppress thosebinary bits which contain information redundant and common to the entirerange of characters thereby compressing the required number of visualsquares to represent a single character to less than eight. In oneembodiment, in which only the letters A through D are anticipated toappear in the first position of an input string, only two visual squaresare required to reflect the four possible binary bit configurations.Where the presence of a dark cell is indicated by "D" and the light cellis indicated by "L," the letter A would be represented as LD. The letterB would be represented as DL, the letter C as DD and the letter D as LL.All represented by using only two cells of visual binary information.Similarly, if in a second character position of the input string it isknown that only numeric values from 0 through 9 will appear, only fourvisual cells need be reserved to accommodate the ten possible binaryvariations for forming this character. Accordingly, in the aboveembodiment, a total of six visual squares or cells need be reserved toreflect the two characters of encoded information rather than thesixteen cells of the US-ASCII system.

The size of the square and the number of cells contained within theperimeter of the square are determined from the code perimeter 11. Solidlines 12 indicate the physical size of matrix 10.

For ease of explanation a square matrix 10 having equal sides 12 ispresented. However any parallagram, such as a rectangle, having an areacomputable by length and height may be used.

Side 14 indicates the density or number of cells 20, 22 contained withinmatrix 10. The number of alternating squares 16, 18 beginning with firstlight square 18 adjacent each perimeter line 12, corresponds to thesquare root of the number of visual cells 20, 22 contained within theperimeter of matrix 10 rounded up to the nearest number. In this examplethe square adjacent perimeter line 12 is a light square 18, however, ina matrix having a different number of cells 20, 22 contained thereinside 14 may begin with a dark square 16 to obtain an appropriate valuefor the number of alternating squares 16, 18.

In an exemplary embodiment, the numerals 0 through 9 are encoded withinmatrix 10 utilizing thirty-six visual cells 20, 22 and being encased ina matrix 10 having a perimeter side 14 containing six alternating darksquares 16 and light squares 18. By providing a perimeter whichindicates the matrix size as well as the number of visual cellscontained within matrix 10 and in binary form, a binary code matrix 10is provided which, as will be discussed below, is recognizable andidentifiable by a scanning computer regardless of physical size orinformation density.

By comparison, a matrix 10A depicted in FIG. 1b contains the sameinformation in the same format as matrix 10 and has a perimeter 11a butat a smaller scale having smaller perimeter sides 12a and 14a.Accordingly, physical size of the code may be unlimited. By providing aformat for indicating to the scanning computer the size and density ofthe matrix in machine readable form, machine readability of a variety ofdifferent size and information density binary codes by a single opticalscanner computer system is possible. In exemplary embodiments, thephysical size may range from one-tenth of an inch square to seven inchessquare, but is limited only by the ability of the user's print device tocreate the selected size.

Reference is now also made to FIGS. 2a through 2d in which thearrangement of visual cells 22 within matrix 10 is depicted, likeelements from FIG. 1a being assigned like reference numerals. Acharacter may be represented by dark visual cells 22a, 22b, 22c, 22d and22e. Visual cells 22a through 22e may be situated in a variety ofpatterns within matrix 10. Visual cells 22 may be in serial order in onecorner of matrix 10 (FIG. 2a), visual cells 22 may be scattered about ineach corner of matrix 10 (FIG. 2b), visual cells 22 may be in reverseserial order in a corner of matrix 10 (FIG. 2c) or they may be randomlydistributed within matrix 10 (FIG. 2d). Each matrix 10 may be keyed to aspecific visual cell placement depending upon the needs of each specificuser. This enables a user to have patterns which are readable by eitherall users of a binary code, or only by specific users of the binarycode, as for example, in top secret verification facilities. A key 23for determining which pattern is used, is encoded in visual cellscontained within perimeter 11 of matrix 10 at a known reference positionwithin matrix 10. For example, key visual cell 23 may be a certaindistance from the intersection of solid lines 12. Additionally, amixture of both public and secret patterns may be present within thesame structure to enable the general public to read part of what iscontained within the matrix 10 and only certain sections of the publicto read what is contained within the rest of matrix 10. In a preferredembodiment, there are 256 pattern variations for situating visual cells22, 23 within matrix 10.

Data 19 may also be stored more than once providing the redundancy inthe information as encoded within matrix 10. Varying levels ofredundancy may be provided by selectively increasing the number ofvisual cells A, B, C, D corresponding to visual cells 20, 22 which areutilized to represent a particular character. At least a three bitdifferential between bit patterns of respective characters of data isutilized so that if a single visual cell 20 or 22 is obliterated thereis still a two bit difference between the bit cell compositionrepresenting respective desired characters. The unique bit combinationso generated also provides the greatest differentiation betweenrepresented characters. Therefore, redundancy is provided by expandingthe number of data bit cells and corresponding visual cells to representa particular character. The redundancy may range from a factor of noredundancy to 400% redundancy. Furthermore, as illustrated in FIGS.3a-3d the redundancy need not be in the same pattern as the root cells.Visual cells A, B, C, D are positioned within matrix 10 a plurality oftimes. The root cell, shown by the darker letters, may be replicated ina mirror image (FIGS. 3a, 3b, 3c) or in a random pattern (FIG. 3d) aslong as identical visual cells such as A, A are not adjacent each other.Accordingly, through redundancy the code is not lost if a portion of thematrix is destroyed or deformed during normal transit or use.

Matrix 10 may be read by the apparatus of FIG. 4. The visual image ofmatrix 10, along with it's surrounding area, is captured by an opticalscanner 24 which converts the visual image into a series of electronicimpulses. Scanner 24 may be a light sensitive electronic array, opticalCCD camera, linear array scanner, laser reader adapted for twodimensional scanning or the like.

The electronic impulses produced by scanner 24 are transmitted to adigitizer 26 which converts these electronic impulses into a series ofcomputer recognizable binary data bits corresponding to the scannedimage. Each visual cell is assigned a binary numeric value based uponthe strength of light sensed by optical scanner 24. Visual cells whichare absolute black and absolute white are assigned the highest andlowest values respectively, while shades in between are assignedincremental values forming an electronic image of the scanned matrix 10.This image is transmitted to a central processing unit of a computer 28("CPU") which stores a bit mapped image of matrix 10 and a part of itssurrounding area as a reference within its memory.

Matrix 10 is not always scanned in a readily discernable orientationrelative to scanner 24. Accordingly, CPU 28 conducts a binary search tolocate the encoded pattern and determine the orientation of matrix 10 asstored in CPU 28. The uniqueness of perimeter 11 of matrix 10 affords areference point. Each matrix 10 contains two solid dark sides 12. CPU 28searches for either solid dark side 12 and upon finding it searches forthe intersection of the dark sides 12. By locating the corner at whichsides 12 intersect, CPU 28 identifies the specific location of matrix 10regardless of size or orientation within the scanned visual field. CPU28 then measures the length of each solid black line 12 stored withinits memory and the angle at which lines 12 intersect. CPU 28 thencalculates where the opposite corner of matrix 10 is located. Byutilizing the length and angle of intersection of sides 12, matrix 10 isalways recognizable even though it may have been subjected tosubstantial linear deformation during the digitizing process as long asthe binary image remains a parallelogram. Additionally, the uniquenessof perimeter 11 allows CPU 28 to differentiate matrix 10 from othersymbols or images within the scan field.

Reference is now made to FIG. 5 in which a flowchart for reading anddecoding matrix 10 is provided. Once the four corners of matrix 10 havebeen identified, CPU 28 counts the alternating dark and light squares16, 18 of perimeter sides 14 in accordance with a step 100. As sides 14are of an identical construction, one side 14 is used as a check againstthe second side 14 to validate the information contained therein in step102. In step 104, CPU 28 calculates the product of the number of squarescontained in each side 14 and determines the density of cells containedwithin matrix 10. By calculating the angle of the matrix, the matrixsize and the matrix density, CPU 28 can calculate the position of eachvisual cell 20, 22 relative to the intersecting lines 12 in accordancewith a step 106. Thus, the center of each visual cell 20, 22 can bedetermined. CPU 28 now knows the physical size of the pattern to bedecoded, the total number of visual cells or their electronic equivalentstored as data 19 and the location of the center of each visual cell 20,22 in relation to the four corners of matrix 10. Since physical size andcell density of matrix 10 are calculated values rather than predefined,CPU 28 may recognize and decode a matrix 10 of any physical size ordensity.

The pattern of data 19 is decoded by first identifying the patterndistribution key in accordance with step 108. The distribution key willalways be stored as a number of visual cells located at a specificposition relative to the corners of matrix 10. Accordingly, in step 110,once the orientation of matrix 10 is determined by CPU 28, CPU 28retrieves from its bit mapped image of matrix 10 the electronicequivalent of the visually encoded key cells. Upon decoding of these keycells, as in step 112, CPU 28 is informed which of the 256 celldistribution patterns was employed to encode data 19 within matrix 10.In accordance with step 114 once the distribution pattern is determined,CPU 28 will reunite the appropriate cells to re-form the binarycharacter strings corresponding to the binary character stringsoriginally input for encoding.

To generate matrix 10, CPU 28 must reverse the process and first convertthe 0, 1 binary language of the computer to the dark/light visual cells20, 22 of matrix 10. CPU 28 calculates the maximum number of charactervariations expected at each position of the input string and thendetermines the minimum number of visual cells required to encode thatnumber of variations. The compression process varies depending on thetype of input character anticipated. For instance, if it is known thatonly numerics will appear at a given input location, the eight bitbinary numbers can be compressed to 3.32 visual cells; if all alphabeticcharacters are anticipated, an eight bit binary letter can be compressedto 4.75 visual cells; or, if the input character could be eitheralphabetic or numeric the compression algorithms reduce each inputcharacter from eight binary bits to 5.21 visual cells.

Further, the system may make use of the available "partial" cells. Forexample, the first alphanumeric character will require six visual cells(smallest integer ≧5.21) while the second alphanumeric character willrequire only five (10.42 cells-6 for the first character=4.42 rounded to5). This allows for the enhanced binary compression as described aboveand thereby further reduces the necessary density of matrix 10. If itwere known as in FIG. 1a, that the ten characters to be input were to beall numeric (0 through 9), CPU 28 would determine through use of thecompression algorithm that the number of potential binary variationscould be accommodated by thirty-four (34) visual cells rather thaneighty (80) visual cells as would be otherwise supposed.

The user then inputs into CPU 28 the type of visual cell distributionwithin matrix 10 desired. The amount of desired redundancy is then inputinto CPU 28 ranging from no redundancy to as high as 400% repetition ofthe pattern. CPU 28 analyzes the pattern of the root visual cell to beencoded and positions the redundant data cells farthest from the rootcell to achieve the highest probability of survival of at least one cellin the event of destruction of a part of matrix 10 (FIGS. 3a, 3b, 3c,3d). The number of visual cells required for the encoded data is thencomputed and added to the number of visual cells required asdistribution key cells to determine the density of matrix 10. The squareroot of this total is then determined to establish the number of squaresrequired to form sides 14 of perimeter 11 of matrix 10. Finally, theuser desired physical size of matrix 10 is input to determine the lengthof sides 12 of matrix 10. Upon calculation of all these values, CPU 28causes a printer 30 to produce the newly generated matrix 10.

By providing a machine readable two dimensional binary code having aperimeter which indicates the physical size of the code on two of itssides and the density of the encoded material on two of its sides, acode which is dynamically variable as to size and density of informationcontained therein is provided.

It will thus be seen that the objects set forth above, among those madeapparent from the preceding description, are additionally attained and,since certain changes may be made in carrying out the above process andin the construction set forth without departing from the spirit andscope of the invention, it is intended that all matter contained in theabove description and shown in the accompanying drawings shall beinterpreted as illustrative and not in a limiting sense.

It is also to be understood that the following claims are intended tocover all of the generic and specific features of the invention hereindescribed and all statements of the scope of the invention which, is amatter of language, might be said to fall therebetween.

What is claimed is:
 1. Apparatus for reading a machine readable codehaving a perimeter and containing a plurality of data elements in atwo-dimensional spatial array representing coded information,comprising:means for sensor scanning a visual field to capture atwo-dimensional image of the visual field; means for converting ascanned visual field image into a bit map representing the scannedvisual field; first processing means for processing the bit map tolocate and determine a size indicia in the bit map, the size indiciaindicating the size of the code and comprising a first solid line and asecond solid line, the first and second solid lines intersecting at afirst corner and forming a portion of the code perimeter; secondprocessing means for processing the bit map, in response to locating thesize indicia, to locate and determine a density indicia in the bitmap,the density indicia comprising a first pattern of alternating lightareas and dark areas and a second pattern of alternating light areas anddark areas, the first and second patterns intersecting at a secondcorner and forming another portion of the code perimeter, the product ofthe numbers of alternating light areas and dark areas in the first andsecond patterns indicating the number of data elements in the coderepresenting coded information; and third processing means responsive tothe determined size indicia and density indicia, for processing thebitmap and determining the coded information in the plurality of dataelements.
 2. The apparatus of claim 1 wherein the sensor scanning meansfurther comprises means for optically scanning a visual field.
 3. Theapparatus of claim 2 wherein the optically scanning means furthercomprises a source of radiation directed to illuminate the visual field,wherein the optically scanning means detects radiation reflected fromthe visual field in response to the illuminating radiation.
 4. Theapparatus of claim 3 wherein the optically scanning means furthercomprises a laser reader having a source of laser radiation and meansfor illuminating the visual field with the laser radiation.
 5. Theapparatus of claim 2 wherein the optically scanning means furthercomprises a light sensitive electronic array.
 6. The apparatus of claim5 wherein the light sensitive electronic array further comprises a lightsensitive area array and a lens to focus an image of the visual fieldonto the area array, wherein a two-dimensional image is captured by thearea array.
 7. The apparatus of claim 6 wherein the light sensitive areaarray and lens further comprise an optical CCD camera.
 8. The apparatusof claim 5 wherein the light sensitive array further comprises a lightsensitive linear array, wherein a two-dimensional image is captured inresponse to the linear array being moved across the visual field.
 9. Theapparatus of claim 3 wherein the optically scanning means furthercomprises a light sensitive electronic array.
 10. The apparatus of claim9 wherein the light sensitive electronic array further comprises a lightsensitive area array and a lens to focus an image of the visual fieldonto the area array, wherein a two-dimensional image is captured by thearea array.
 11. The apparatus of claim 10 wherein the light sensitivearea array and lens further comprise an optical CCD camera.
 12. Theapparatus of claim 9 wherein the light sensitive array further comprisesa light sensitive linear array, wherein a two-dimensional image iscaptured in response to the linear array being moved across the visualfield.
 13. A method for scanning a machine readable code having aperimeter and containing a plurality of data elements in atwo-dimensional spatial array representing coded informationcomprising:scanning a visual field and capturing a two-dimensional imageof the visual field; converting a captured visual field image into a bitmap representing the scanned visual field; processing the bit map tolocate and determine a size indicia in the bit map, the size indiciaindicating the size of the code and comprising a first solid line and asecond solid line, the first and second solid lines intersecting at afirst corner and forming a portion of a perimeter of the code the sizeindicia; further processing the bit map, in response to locating thesize indicia, to locate and determine a density indicia in the bitmap,the density indicia comprising a first pattern of alternating lightareas and dark areas and a second pattern of alternating light areas anddark areas, the first and second patterns intersecting at a secondcorner and forming another portion of the perimeter of the code, theproduct of the numbers of alternating light areas and dark areas in thefirst and second patterns indicating the number of data elements in thecode representing coded information; and determining the codedinformation in the plurality of data elements in response to thedetermined size indicia and density indicia and the bitmap.
 14. Themethod of claim 13 wherein the scanning step further comprises providinga light sensitive device, detecting radiation reflected from a visualfield containing the code, and forming a two-dimensional electronicrepresentation of the visual field in response to the detected reflectedradiation.
 15. The method of claim 14 wherein the step of detectingradiation further comprises illuminating the visual field withradiation, wherein the detected reflected radiation is responsive to theilluminating radiation.
 16. The method of claim 14 wherein the step ofdetecting radiation further comprises generating laser radiation,illuminating the visual field with said laser radiation, and detectingthe radiation reflected in response to the laser radiation.
 17. Themethod of claim 14 wherein the step of detecting radiation furthercomprises providing a light sensitive electronic array and capturingelectronic data corresponding to a two-dimensional image of the visualfield.
 18. The method of claim 17 wherein the step of providing a lightsensitive array further comprises providing light sensitive area arrayand a lens, focussing an image of the visual field on the area array,and capturing a two-dimensional electronic representation of the scannedvisual field.
 19. The method of claim 18 wherein providing a lightsensitive area array and a lens further comprises providing an opticalCCD camera.
 20. The method of claim 18 wherein the step of providing alight sensitive array further comprises providing a linear array, andmoving the linear array across the visual field and capturing atwo-dimensional electronic representation of the visual field inresponse to said movement.
 21. The method of claim 15 wherein the stepof detecting radiation further comprises providing a light sensitiveelectronic array and capturing electronic data corresponding to atwo-dimensional image of the visual field.
 22. The method of claim 21wherein the step of providing a light sensitive array further comprisesproviding light sensitive area array and a lens, focussing an image ofthe visual field on the area array, and capturing a two-dimensionalelectronic representation of the scanned visual field.
 23. The method ofclaim 22 wherein providing a light sensitive area array and a lensfurther comprises providing an optical CCD camera.
 24. The method ofclaim 21 wherein the step of providing a light sensitive array furthercomprises providing a linear array, and moving the linear array acrossthe visual field and capturing a two-dimensional electronicrepresentation of the visual field in response to said movement.